


Cú Selfcest

by Lady_Rhey



Series: The Men of Fate (Yaoi) [4]
Category: Fate/Grand Order, Fate/stay night & Related Fandoms
Genre: M/M
Language: English
Status: In-Progress
Published: 2019-01-19
Updated: 2019-01-19
Packaged: 2019-10-11 11:18:30
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 4,201
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17445941
Author URL: https://archiveofourown.org/users/Lady_Rhey/pseuds/Lady_Rhey
Summary: AO3 Request: Could i maybe request some Cu x Cu selfcest ? Proto x Lancer, or Caster x Lancer, or Alter x Caster, I have no preference just whichever you'd prefer!So I ABSOLUTELY LOVE Cú.  That means I am not holding back on any chapter/request that involves him so don't be surprised if these scenes are long. xD





	1. Sex Ed (Cú Alter x Caster Request)

You know the saying "If you want something done right you have to do it yourself?"  Imagine how true that is when there is three of you.  Three of you ready, willing and able to do it just the way you like it.....because after all.....you are the one doing it.  Literally.

 

Lancer had it rough.Unlike Caster, whose Master was a freak in bed as well as a total nympho, and Alter, whose Master was a total sub and let him do whatever he wanted whenever he wanted, Lancer's Master was a virgin.When I say that I don't mean she was some vanilla snowflake, I mean she was LITERALLY a virgin.You would think that would make it more exciting, but Lancer wasn't into deflowering some child.This was mainly because of all the emotional drama that came with it.

 

Sadly this left him with a permanent state of blue balls since she, finding him undeniably attractive, kept finding ways to proposition him with and without clothes on. 

 

He had tried pleasuring himself, but it never left him fulfilled.It also left him open to attack from his Master who had walked in on him more than once.

 

At this rate, he would have to find someone else who could get it done for him that wouldn't leave him with emotional baggage.The question was, where was he going to find a person like that? 

 

Lancer sighed heavily as he sat on the bench in the garden, his head leaned back and his eyes closed waiting for his partial erection to go down.  His Master had been especially aggressive in her affections today and it wasn't until now, when she had training to attend, that he had been able to get away.  So far this small, partially walled off area with a bench had been his only sanctuary, seeing as it was tucked away inside the garden maze and Master wasn't very good at puzzles of any kind.

 

As he sat there in silence listening to the people ebb and flow around him, he wondered if he would be more fulfilled if he added a little spice to his self love.  The possibility of Master seeing him terrified him, but the thought of someone not Master......

 

He could feel his dick getting hard just at the thought of someone random coming by and seeing.  The reality was there was a 50 50 chance they would be grossed out or turned on as well, so he might be able to kill 2 birds with one stone. 

 

Still leaning back, partially blocked by the half wall behind him that rose above his head a foot, Lancer reached down with one hand and began running his fingers on either side of his growing length in long.....slow strokes. 

 

It really was more exhilarating to do these kinda things in public he mused as his mouth opened slightly when his fingers increased their pressure and speed, bringing him to full erection in seconds. 

 

Realizing he needed more skin to skin contact, but that not wearing any pants might not be the best call, he materialized a pair of single button fly sweatpants and a loose fitting T-shirt before snaking his hand inside the fly and grasping his shaft with one hand as he pulled on his pony tail with the other. 

 

This was feeling better and better by the moment.  So good in fact that he allowed himself a quiet sigh of pleasure.

 

"My my such a disgraceful sight.  I knew your Master and you didn't see eye to eye sexually, but I had no idea you needed to take it this far."

 

The voice neither startled nor embarrassed him and he could hear amusement mixed with lust in the huskier voice as Caster's purposeful steps came to a stop in front of him. 

 

Opening partially hooded eyes, Lancer smiled up at his alter self.  All the Cú's were close, like brothers, seeing as they were essentially the same person so there was no reason to feel embarrassed in his current state.  "I have to get release somehow.  That needy virgin won't leave me alone, but that doesn't mean it doesn't still have an affect on me. 

 

Lancer continues to stroke himself as his and Casters eyes meet.

 

"Well little brother, a pet name Caster had for him seeing as he was the older of the two in the timeline, if you had just told me I might have been able to help."

 

"Is that so?  And what could you have done?  Would you have had sex with her in my place so I wouldn't have to be the one to ruin all men for her going forward?"  Lancer smirked. 

 

"On the contrary."  He said as he took Lancer's hands and placed them on the back of the bench before binding them with branches from the bush to the bench frame.  "We could have done THIS in a more romantic setting, but seeing as it turns you on so much, I guess you just have to be as quiet as you can.  Though I will provide a little buffer should anyone think to enter."  With that, Caster closes the gap between the wall behind them and the wall perpendicular to them so they are now walled in and the only view anyone can get is if they peek over.

 

That finished, Caster kneels down between Lancers legs as he traces the tips of his fingers down his chest and across his pelvis before slipping his hand into his pants to encircle the man's raging hardon. 

 

"As impressive as I would imagine given your class."  Caster looks into Lancers needy eyes with one last smirk before running his tongue up and down Lancer's throbbing member, causing the latter to bite his lip and ball his hands into fists as the unexpected pleasure of Casters' touch snakes up his body. 

 

"So innocent.  If this is all it takes to get you going, I can't wait to see what happens when we are alone.  That is, of course, if you want to do this again."

 

With Lancers' shaft slick from Casters' ministrations, Caster places his lips over the tip and begins to suck as his tongue slides over and into his slit. 

 

Lancers' head shoots back as his eyes roll up, a silent gasp escaping his parted lips. 

 

"Mmmmnnn I could get used to watching you squirm."  Caster says, releasing Lancers bulb for a second before enveloping and sliding halfway down the shaft as he begins fondling his balls. 

 

"Is it worse because you can't touch me?  Do you want to put your lips on my skin and yank my hair little pup?"  Casters' voice says in Lancers' mind. 

 

"Fuck you feel amazing.  I just want to tear into you, but these damn manacles..."

 

Lancer strains against his restraints for a second, but Caster stops him as he suddenly takes all of Cú in his mouth as he increases his pace and the pressure of his suck on his victim. 

 

"Now now, just sit back and enjoy." 

 

Lancer, seeing no other option, begins rocking his hips into Casters' lips craving the feeling of penetrating him deeper. 

 

Caster hums, sending delicious vibrations  over Lancer that has him whining quietly with need. 

 

"Are you ready to cum little brother?  I'm dying to see what you taste like."

 

Then Caster wraps his pointer finger and thumb around the base of Lancers cock creating a tighter cock ring that he rises and falls with his pumps increasing the pleasure he gives enough that Lancer tries to slam into his face. 

 

Within moments, Caster can feel Lancers cock begin to contract, signaling his approaching orgasm. 

 

"That's it.  Cum hard for me little brother.  Show me how badly you want my lips on your dick."

 

Then with a final grunt and upward thrust of his hips, Lancer unloads into Casters sultry mouth. 

 

With ease, Caster swallows it all before gently sucking every lady drop from the twitching Lancer. 

 

When his body is lax and his member decreasing, Caster releases him with an exaggerated suck before removing the manacles and tucking Lancer back into his pants.

 

"Seems like that is exactly what you needed."  Then he licks his lips as he stares into Lancers eyes. 

 

"Hmmmn."  Lancer says with a smile before sitting up, placing his face lip level to Casters cock. "What about you?"  He says as he grabs Casters ass with one hand before gently taking his slightly hard member between his teeth and squeezing.

 

"Since you asked..." Caster replies as he runs his hand through Lancers hair ".....I was on my way to see Alter.  He's a beast in bed you know and I need a little carnal love right now."

 

Lancer removes his lips and pouts up at his other self. 

 

"Don't be sad."  Caster runs the back of his fingers over Lancers cheek.  "I'm sure he won't mind if we add another."  Caster winks and Lancer smiles mischievously.

 

——————————

 

Alter hated waiting.  He hated most things actually, but sex was not something he wanted to wait for and he despised Caster for constantly pushing his buttons. 

 

*knock knock*

 

Then the door opened and Alter growls signaling his displeasure, but his complaint is cut short when he sees Caster followed by Lancer. 

 

"Sorry I'm late hunny, I picked up a stray." 

 

Alter just glares at them from the bed he is seated on. 

 

"Don't worry, he's just taking it all in.  His personality takes some getting used to, but I promise it's not his best asset."

 

"Shut your damn mouth and get naked."  Alter commands as he looks at Caster with a predatory glare. 

 

"Always the romantic."  Caster sighs before disrobing and walking over to Alter.  "Guess you will start out watching kiddo.  He has to assert dominance."

 

Lancer is surprised by the affection he hears in Casters voice as he says that, but is even more shocked by the level of intimacy between the two. 

 

When Caster stands before Alter, their eyes locked, Alters clawed hand reaches out and gently rests on his lower back as he pulls Caster in for a kiss. 

 

Though the kiss is forceful, Caster slides one hand under Alters hood to tangle in his hair as his other rests on his shoulder as Alter goes between kissing deeply and tugging harshly on his bottom lip.

 

Soon Alters' hand moves to Casters' ass, digging his fingers into his flesh as the middle finger slips into the crack at the same time his lips trail nips and licks down Casters neck eliciting pleasant moans.

 

Lancer would never have guessed that the Berserker had tenderness in him.  It was a phenomena he couldn't tear his eyes from.

 

As the kisses got lower, Alter began shifting back on the bed until Caster knelt on his knees above him as he straddled his pelvis. 

 

When Alters' lips reached the base of Casters neck he hummed before shifting his hand to his hip as his lips traveled halfway across his shoulder.

 

Then, when his lips reached the meatiest part of Casters shoulder, he bit down hard, penetrating skin as he sheathed himself deep into Casters' ass.  There was no way that didn't hurt, but in a way Lancer was sure the bite hurt worse than the penetration, probably the only kindness Alter could give not having any concept of pleasure in any form not laced with pain. 

 

"Alter...." Caster whined in a needy, more feminine voice as he clutched at the Berserkers neck before searching for and enveloping his lips.

 

Alter growled low in his chest, setting a harsh pace as his hand began pumping Casters dick.

 

As Lancer watched, he saw a strange bond of lust travel between the two and he suddenly felt jealous. 

 

It was in that moment of jealousy that Alter finally looked his way with a sadistic grin that sent desire coursing right to Lancers head.

 

Kissing Caster one more time, he pulled out and flipped his panting body around so Caster faced Lancer before penetrating him again slowly. 

 

Caster looked at Lancer with lust in his eyes as he put his arms behind him to wrap around Alters' neck, exposing his raging erection to Lancer.

 

Lancer couldn't resist.  Waking over to Caster, he took the man completely in one slide that he timed to Alters' pump.  Though it took a few tries, the three began moving in sync as Alter fucked Caster and Caster fucked Lancer, while Lancer played with himself. 

 

The pace was slow and tormenting, but that only meant the end result was that much better.  Caster had never been double teamed so he caved first, screaming in unbridled release as his orgasm shot into Lancers mouth at the same time Alter bit his neck and slammed his prostrate.  

 

When he could stand, he separated from the two and smiled at Lancer.  Good luck kid, he's an acquired taste."

 

With that, Lancer found himself lip locked with Alter as his tongue slid into his mouth, Alters' desire to taste Casters' release overwhelming him.

 

As they locked in a kiss, Alter picked up Lancer and laid him on the bed before ripping off his pants, grabbing his dick and penetrating him, stealing his cries and moans as he lifted Lancers legs to his shoulders setting another harsh pace.

 

Though rougher than he was used to, there was a definite eroticism to being dominated by the Berserker.  As the pounding continued and Lancer stopped thinking, he felt the pleasure rising in his core.

 

"Fuck Alter.  Go deeper."

 

Alter growls and nips at his neck in its soft spot below his jaw before pushing into him harder. 

 

"Ahhhh....yes.....that's it....more..."

 

Lancers' fingers penetrate Alters' hood as one hand tangled in his hair while the other yanks on his pony tail. 

 

"Fuck me like your little bitch you monster."  Then Lancers lips smash into Alters before biting hard enough to draw blood on his lower lip. 

 

In the next instant Lancer is on all fours as Alter rides him like a dog from behind, pulling on his pony tail hard enough that his head cranes back with one hand as he jacks him off with the other. 

 

The pain......the pleasure......

 

"Cum for me like the bitch you are."  Alters' deep, husky voice penetrates his soul as the words are whispered in his ear. 

 

It was more than Lancer could take.  Crying out his ecstasy as Alters' strong grip pumps him one final time, he explodes into the sheets in front of him as Alter releases inside him. 

 

When the high is gone, Lancer feels a clawed hand gently run down his back and over his hip before Alter pulls out. 

 

"He likes you, otherwise you would be a tattered mess left for me to heal."

 

Lancer gingerly backs off the bed before turning to look at Alter who is leaning against the wall with his tail casually wagging up and down. 

 

"I'll have to take your word for it."  Lancer says skeptically.  "Well I'm sure three is a crowd and I doubt he cuddles so, I'll be going."  With that, Lancer walks to the door, but Castor stops him with a hand on his arm.

 

"You are welcome to join me or us anytime."  Then he smiles and releases his hand.

 

"I'll keep that in mind."  Then Lancer brushes Castors' lip with his thumb before walking out the door.


	2. Sex Ed (Cú Alter x Caster Request)

Caster had always been seen as the most mature of the 4.5 Cú's that existed (Smol Cú making up .5).He didn't mind being seen that way, except when it came to sex. 

 

For some reason everyone he tried to get with had this strange notion that maturity meant he was above base desires, had no kinks, and would be the perfect romantic partner (the last being the ONLY accurate assessment. 

 

How wrong everyone was.He might be the most mature, but he was definitely the most sexually deviant.It was actually his deviance that kept him from having a long term relationship with anyone......at least until Alter. 

 

Caster had never really put much stock

in Alter outside of the battlefield.He seemed to have two settings: on and off. In the field he was ravenous, destroying anything and everything he could get his hands on that breathed.Back home he remained dispassionate, uninterested and hateful of everything. 

 

What he hadn't seen were the hooded looks Alter gave him when Caster wasn't looking or the fact that Alter always tried to be where Caster was, even if he didn't notice him. 

 

It wouldn't be until the 'misunderstanding@ with Jean's Master that Alter got his chance. 

 

For once Ater genuinely happened to be going in this direction, when he saw the whole thing play out. 

 

"I absolutely WILL NOT put that there!What is wrong with you!You are such a pervert!"She screamed at Caster as she stood crying, half dressed outside his door before running down the hall in tears. 

 

Seconds later Alter was face to face with a mostly naked Caster who clutched a towel to his hips as he staggered out the door in an attempt to follow the girl. 

 

"Damnit you aren't her!"Caster said in frustration as he looked around Alter to see the hallway empty."Fuck!"He sighed before looking up at Alter who just raised an eyebrow with a dispassionate look on his face."Or I guess not."Caster replies morosely before walking back into his room. 

 

Not quite the invitation he was looking for, but beggars can't be choosers.  Once inside, Alter closes the door before finding a place against the wall. 

 

"I don't understand why women aren't more open about sex.  Experimenting isn't a bad thing and just because something seems odd doesn't mean you aren't going to like it."  Caster sighs.  "She didn't even try to see my side of it."

 

Alter can hear the bitterness and disappointment in his voice as Caster heads into the bedroom and, despite not being able to sympathize, chooses to follow him in. 

 

Once inside, he sees a handful of sex toys as well as soft core bondage pieces laid out on the bed, though Caster is nowhere to be found. 

 

Curious, Alter reaches out to touch a flimsy plastic rod that is lined with balls of various sizes.

 

"Those are anal beads." Caster says casually as he rubs a towel over his damp hair causing the towel at his hips to loosen slightly.Essentially, they enhance pleasure by allowing double penetration.That is what caused that pretty little thing to run out the door.It wasn't even for her, but it didn't matter."

 

Caster sighs heavily before laying down on an empty space on the bed."All I wanted was a fresh perspective, but miss prissy pants couldn't handle it.Girls.Must be nice to be that naive."

 

Because Alter wasn't one to miss an opportunity that benefitted him, he chose to act on his instinct.

 

"A fresh perspective.Is that all you wanted?"Still holding the beads, he slowly walks around the bed until he is standing at its foot.

 

Cú raises himself up so he is resting on his elbows, his eyes looking quizzically at Alter.

 

"If I had to be honest I would say that I wanted someone other than that sex crazed Master of mine to play with me now and again so it felt more like love and less like a freak show."

 

Love....not an emotion Alter had any understanding of.Attraction he understood.Longing he was aware of.Love.....completely foreign. 

 

"Have you thought about asking someone you already know or are close to to help?Less drama that way."Alter says as he glances at Caster from underneath his hood.

 

"Heh.And which one of the people I know is gonna help me fuck me?"

 

That's when Alter grabs him by the ankle and pulls Caster to him before spreading his legs enough to allow Alters' torso to slip through so his tongue can slide from Casters' navel to his neck.

 

"I, for one, would be more than willing to do it."Not being one to ask for permission or consent, Alter slid a hand under Cú's ass and squeezed, digging his clawed fingers into the soft flesh slightly as he nipped at Casters' neck. 

 

Caster, both highly aroused at Alters' forwardness as well as freaked out by the possibility that he would end up dead if Alter went sexually berserk in bed, put his hands on Alter's shoulders, trying to brace against him and squirm out of his grip.

 

"Whoa there big guy, I'm not looking to get eviscerated when you go sexually berserk."  Caster said with slight anxiety in his voice. 

 

Alter just smirks before haphazardly flipping Caster over and pulling his hips up.  "Don't get too comfortable on your knees.  I'm looking forward to having you everywhere possible.  Then Alter grabs the lube next to the bed and coats the anal beads, before bending Caster in half and sneering."Let's see if these beads were worth her getting so upset."

 

As Alter inserted the beads, his other hand cupped and then began to stroke Casters shaft.Never caring about intimacy or what his actions did to others, Alter found it exhilarating to see Caster writhe in ecstasy underneath him.The mans moans were, at their base, similar to the sounds made when one was dying except there was no blood or mess.He also couldn't deny how immensely satisfying it was to have Caster beg for him to do more.He always got so bored when people begged for their life, but this.....this was far more satisfying. 

 

"Alter.......please..." Caster whined trying to ride the beads as Alter pushed them in and out slowly "harder....faster...."

 

Alter purred as he bit down on Casters hip and increased the pressure on his cock before elevating the depth and pace of the beads.

 

"Fuck....me."  Caster managed to eek out in between carnal moans as his body began to shudder. 

 

Alter took that as a proposition, not a statement.  Taking the beads out, he dematerialized his armor before grabbing Casters hips and sliding himself inside as he lifted Caster up so he laid upright against his chest. 

 

Caster gasped and put his hands behind him, snaking the fingers under Alters' hood and tangling them in his hair. 

 

With one clawed hand on Casters chest, the other slowly slid slowly down his torso before encircling his pulsing member. As Alter began to stroke again, he bit and kissed Casters neck as he pumped in and out with enough force to hit Casters' prostate easily. 

 

Biting his lip, Caster spread his legs slightly farther as he began riding Alter in reverse, allowing the Berserker to penetrate even deeper. 

 

As Alters pleasure rose, he found it increasingly difficult not to rake his hand down Casters body, afraid he would slice him open. 

 

That's when one of Casters' hands detached from his hair and came to rest atop his, Casters fingers resting above each of his. 

 

Carefully, Caster pressed into Alters' fingers until he reached his desired pressure.  Once optimal pressure was obtained, Caster guided Alters' hand down his chest, letting him know how he should touch him. 

 

Alters' tail whipped to the side in anticipation as he bent Caster so he rested on his hands and knees, freeing up Alters hand on his chest.  

 

Caster then reached down and took the hand that held his cock and placed it on his hip before replacing it with his own. 

 

"Just touch me and fuck me."  Caster said in a needy voice.

 

Growling deeply, Alter sat up and rested both hands on Casters’ hips as he continued to penetrate him over and over, digging his nails into the sensitive flesh of his ass and pelvis.After a few thrusts, Alter took one hand and ran it up his back, dragging his claws over the skin in the way Caster showed him. 

 

As Casters’ moans increased, Alter took his pony tail and wrapped it around his hand before pulling it enough that Casters’ head tilted back.Needing more leverage, Alter then moved his other hand from Casters hip up to his shoulder allowing him to pump into him harder.

 

It wasn’t long after that that the two gave in to release.Alter released Casters hair, sliding his hands down to rest on his thighs as Caster rested his head on the mattress, both panting.

 

Several moments passed before Alter pulled out and rematerialized his armor as he got up off the bed. 

 

Caster rose and turned to look at him, giving a faint smile.“Not the cuddling type I see.”

 

Alter grinned before wrapping his tail around Caster and pulling him against him, taking his chin in his hand as he kissed him with the last of his passion.

 

Caster was speechless.The sex, the kiss, and now the retreating form of Alter as he left his room without another word or look.That Berserker was an anomaly, but one he found himself wanting to indulge in again and again. 


End file.
